Index: src/Parser/parser.yy
===================================================================
--- src/Parser/parser.yy	(revision 65ef0cd7e951937056fb71e81989690e7e2717cc)
+++ src/Parser/parser.yy	(revision b4d2b3b4081619a689af90fcbf6d98aad4304dbd)
@@ -10,6 +10,6 @@
 // Created On       : Sat Sep  1 20:22:55 2001
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Tue Jun 20 22:10:31 2023
-// Update Count     : 6348
+// Last Modified On : Fri Jun 30 12:32:36 2023
+// Update Count     : 6364
 //
 
@@ -2680,10 +2680,11 @@
 	ENUM attribute_list_opt '{' enumerator_list comma_opt '}'
 		{ $$ = DeclarationNode::newEnum( nullptr, $4, true, false )->addQualifiers( $2 ); }
+	| ENUM attribute_list_opt '!' '{' enumerator_list comma_opt '}'	// invalid syntax rule
+		{ SemanticError( yylloc, "syntax error, hiding '!' the enumerator names of an anonymous enumeration means the names are inaccessible." ); $$ = nullptr; }
 	| ENUM attribute_list_opt identifier
 		{ typedefTable.makeTypedef( *$3 ); }
 	  hide_opt '{' enumerator_list comma_opt '}'
 		{ $$ = DeclarationNode::newEnum( $3, $7, true, false, nullptr, $5 )->addQualifiers( $2 ); }
-	| ENUM attribute_list_opt typedef_name				// unqualified type name
-	  hide_opt '{' enumerator_list comma_opt '}'
+	| ENUM attribute_list_opt typedef_name hide_opt '{' enumerator_list comma_opt '}' // unqualified type name
 		{ $$ = DeclarationNode::newEnum( $3->name, $6, true, false, nullptr, $4 )->addQualifiers( $2 ); }
 	| ENUM '(' cfa_abstract_parameter_declaration ')' attribute_list_opt '{' enumerator_list comma_opt '}'
@@ -2694,8 +2695,12 @@
 			$$ = DeclarationNode::newEnum( nullptr, $7, true, true, $3 )->addQualifiers( $5 );
 		}
+	| ENUM '(' cfa_abstract_parameter_declaration ')' attribute_list_opt '!' '{' enumerator_list comma_opt '}' // unqualified type name
+		{ SemanticError( yylloc, "syntax error, hiding '!' the enumerator names of an anonymous enumeration means the names are inaccessible." ); $$ = nullptr; }
 	| ENUM '(' ')' attribute_list_opt '{' enumerator_list comma_opt '}'
 		{
 			$$ = DeclarationNode::newEnum( nullptr, $6, true, true )->addQualifiers( $4 );
 		}
+	| ENUM '(' ')' attribute_list_opt '!' '{' enumerator_list comma_opt '}'	// invalid syntax rule
+		{ SemanticError( yylloc, "syntax error, hiding '!' the enumerator names of an anonymous enumeration means the names are inaccessible." ); $$ = nullptr; }
 	| ENUM '(' cfa_abstract_parameter_declaration ')' attribute_list_opt identifier attribute_list_opt
 		{
@@ -2709,16 +2714,13 @@
 			$$ = DeclarationNode::newEnum( $6, $11, true, true, $3, $9 )->addQualifiers( $5 )->addQualifiers( $7 );
 		}
-	| ENUM '(' ')' attribute_list_opt identifier attribute_list_opt
-	  hide_opt '{' enumerator_list comma_opt '}'
+	| ENUM '(' ')' attribute_list_opt identifier attribute_list_opt hide_opt '{' enumerator_list comma_opt '}'
 		{
 			$$ = DeclarationNode::newEnum( $5, $9, true, true, nullptr, $7 )->addQualifiers( $4 )->addQualifiers( $6 );
 		}
-	| ENUM '(' cfa_abstract_parameter_declaration ')' attribute_list_opt typedef_name attribute_list_opt
-	  hide_opt '{' enumerator_list comma_opt '}'
+	| ENUM '(' cfa_abstract_parameter_declaration ')' attribute_list_opt typedef_name attribute_list_opt hide_opt '{' enumerator_list comma_opt '}'
 		{
 			$$ = DeclarationNode::newEnum( $6->name, $10, true, true, $3, $8 )->addQualifiers( $5 )->addQualifiers( $7 );
 		}
-	| ENUM '(' ')' attribute_list_opt typedef_name attribute_list_opt
-	  hide_opt '{' enumerator_list comma_opt '}'
+	| ENUM '(' ')' attribute_list_opt typedef_name attribute_list_opt hide_opt '{' enumerator_list comma_opt '}'
 		{
 			$$ = DeclarationNode::newEnum( $5->name, $9, true, true, nullptr, $7 )->addQualifiers( $4 )->addQualifiers( $6 );